FDA Approves Hibsago as First Antisense Therapy for Chronic Hepatitis B

The FDA has approved bepirovirsen (Hibsago, GSK) injection, in combination with existing antiviral therapy, to treat chronic hepatitis B virus (HBV) infection in certain adults without cirrhosis. Bepirovirsen is the first FDA-approved antisense oligonucleotide for chronic hepatitis B, according to the agency.

The drug is approved for adults without cirrhosis who have taken HBV antiviral therapy for at least 6 months, have suppressed blood levels of HBV, and have hepatitis B surface antigen (HBsAg) levels of 3,000IU/mL or less, as determined by an FDA-authorized test. The FDA also authorized the Roche Elecsys HBsAg II quant II RxDx assay as a companion diagnostic to aid patient selection and monitoring during treatment.

According to the FDA, bepirovirsen targets the genetic instructions HBV uses to replicate and make viral proteins, helping reduce levels of virus and HBsAg. It is injected subcutaneously for up to 24 weeks alongside existing hepatitis B medicine, which patients continue for at least 24 weeks after the last bepirovirsen injection. Some patients may then be able to stop their existing medicine if they meet certain health and laboratory requirements.

In 2 placebo-controlled trials, 24% of patients who received bepirovirsen met the requirements to stop their existing medicine, compared with none who received placebo. Twenty-four weeks after stopping all hepatitis B treatment, 19% of patients who received bepirovirsen still had the virus under control and undetectable HBsAg.

Bepirovirsen carries a boxed warning for serious liver reactions and for low platelet counts, which can increase the risk of potentially life-threatening bleeding. Additional warnings cover worsening kidney function, serious inflammatory adverse reactions such as vasculitis, and serious risks with improper administration. Patients need regular blood tests and follow-up before and during treatment. The most common side effects, excluding laboratory abnormalities, are injection site reactions, fever, fatigue, and headache.

The FDA granted bepirovirsen Fast Track and Breakthrough Therapy designations and Priority Review.

Source: US Food and Drug Administration. FDA approves first-of-its-kind chronic hepatitis B treatment. Press release. US Food and Drug Administration; October 20, 2026. Accessed October 20, 2026.